Lithium and sodium ion binding energies of N-acetyl and N-glycyl amino acids

Wan Yong Feng, Scott Gronert, Carlito B Lebrilla

Research output: Contribution to journalArticlepeer-review

45 Scopus citations

Abstract

Using a quadrupole ion-trap mass spectrometer with an electrospray ionization source, the Cooks kinetic method has been used to measure the lithium and sodium ion binding energies of the N-acetyl and N-glycyl derivatives of a series of 14 amino acids. For comparison, the gas-phase basicities of the amino acid derivatives were also determined by the kinetic method. The lithium binding free energies range from 47.2 to 56.4 kcal/mol, and the sodium affinities from 30.8 to 41.2 kcal/mol. Comparisons between basicities and metal ion binding energies indicate that the presence of a coordinating group (e.g., -OH, -CO2H, etc.) in the amino-acid side chain can significantly increase the lithium and sodium binding energies. Dynamics calculations (CHARMm) confirm that side-chain coordination is a common stabilizing effect in the metalated systems. A good correlation, with a slope near unity, is found between the metal ion binding energies of the N-acetyl and N-glycyl derivatives. This indicates that the two groups of compounds are adopting similar coordination schemes and strongly suggests that zwitterionic forms of the peptide derivatives are not important.

Original languageEnglish (US)
Pages (from-to)1365-1371
Number of pages7
JournalJournal of the American Chemical Society
Volume121
Issue number6
DOIs
StatePublished - Feb 17 1999

ASJC Scopus subject areas

  • Chemistry(all)

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